This work will investigate the development of a cell culture system containing normal human bronchial epithelial (NHBE) cells and a serum-free optimized medium for their growth. Serum-free culture of normal human cells is a major technological advance which facilitates research into human diseases. Normal human bronchial epithelial (NHBE) cells have been grown successfully in serum-free medium and are a valuable tool in the study of diseases of the respiratory tract such as lung cancer, cystic fibrosis and asthma. In order to make this system commercially available to the industrial, academic, and medical community, research is needed to optimize and develop this cell system into a reproducible, quality assured product. Culture parameters must be investigated to determine plating density, growth rates and cellular senescence, cryopreservation procedures, morphologic characteristics (to assure a non-differentiated cell population) and antigenic determinants. The knowledge from the above research will be used to optimize a culture medium for the proliferation of NHBE cells. This culture system will facilitate research by eliminating the researchers' need to support a comprehensive tissue culture laboratory.